Fecal sampling was done to evaluate changes in the microbiome of the gut and to detect colonization of opportunistic pathogens.

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SAN DIEGO – The use of SYN-004 (ribaxamase) is effective for maintaining gut microbiome balance and may prevent opportunistic infections, such as Clostridium difficile infections (CDI) during treatment with intravenous (IV) β-lactam, according to findings from a multinational phase 2b double-blind placebo-controlled trial presented by lead investigator John Kokai-Kun, PhD, vice president of non-clinical affairs at Synthetic Biologics, Inc. in Washington DC, during an abstract session at IDWeek 2017.

“CDIs are an urgent threat, but there are no approved drugs or vaccines to prevent new onset CDI,” according to Dr Kokai-Kun. Ribaxamase can be administered to degrade antibiotics, potentially preventing disruption of the gut microbiome from CDI, antibiotic resistance, and colonization of the intestines by opportunistic pathogens.

The investigators in this trial sought to evaluate the effectiveness of ribaxamase in the prevention of new onset CDI. Secondary end points included non-CDI antibiotic-associated diarrhea, changes in the gut microbiome, antibiotic resistance rates, and colonization by opportunistic pathogens.

A total of 412 patients in the modified intention-to-treat population who received IV ceftriaxone for the management of a lower respiratory tract infection were included. Subjects were randomized to receive either ribaxamase or placebo for the duration of treatment and 72 hours after treatment.

Following a 6-week monitoring period and the examination of fecal samples, investigators found that the study met its primary end point. In addition, there was a 71% risk reduction in CDI (P =.045) and a 44% relative risk reduction in new colonization by opportunistic pathogens, specifically vancomycin-resistant enterococci (P =.0002).

“Ribaxamase also protected the diversity of the gut microbiome and reduced the emergence of antibiotic resistance in ceftriaxone-treated patients,” added Dr Kokai-Kun.